Tube surface scraping

ABSTRACT

A phosphor coating is removed from a tube by holding a scraper against an interior wall with a magnet and moving the magnet, thus moving the scraper and scraping the coating from the wall. The scraper has several spaced parallel blocks with arcuate scraping edges slightly offset from each other. The blocks are joined by a resilient band which permits relative movement. A plurality of magnets is fixed in a parallel assembly, so that each scraping block forms an armature for one magnet.

United States Patent Hulvey et al.

Oct. 1, 19174 TUBE SURFACE SCRAPING Inventors: William L. Hulvey, Springfield;

Clive S. Axtell, Vienna, both of Va.

Assignee: The Richards Corporation, McLean,

Filed: Mar. 27, 1972 Appl. No.: 238,423

U.S. Cl 134/8, 15/104.16, 15/220 A Int. Cl B08b 9/02 Field of Search 15/104.16, 104.05, 250.28,

15/220 A; 73/324; 259/DIG. 46; 134/6, 8

References Cited UNITED STATES PATENTS Penn l5/l04.06 R Hendrey 15/220 A UX Leith, Jr. 15/104.l6 X

FOREIGN PATENTS OR APPLICATIONS 856,978 12/1960 Great Britain 15/220 A Primary Examiner-Edward L. Roberts Attorney, Agent, or Firm-James C. Wray [57] ABSTRACT A phosphor coating is removed from a tube by holding a scraper against an interior wall with a magnet and moving the magnet, thus moving the scraper and scraping the coating from the wall. The scraper has several spaced parallel blocks with arcuate scraping edges slightly offset from each other. The blocks are joined by a resilient band which permits relative movement. A plurality of magnets is fixed in a parallel assembly, so that each scraping block forms an armature for one magnet.

13 Claims, 3 Drawing Figures TUBE SURFACE SCRAPING BACKGROUND OF THE INVENTION Tubes of many kinds have requirements for treating of particular areas of surfaces. Treating is especially difficult when an interior surface must be reached. The difficulty is increased when operating must be removed from a closely defined area on an internal tube surface, far from an end of an elongated tube.

One example of a tube which must be physically treated to remove a coating is described in U.S. Pat. No. 3,141,990. An aperture lamp is a special form of a fluorescent lamp from which a portion of the phosphor coating is removed to produce a high intensity light directed through the aperture.

A fluorescent tube is made of a glass envelope interiorly coated with phosphor. Gas sealed within the tube becomes ionized upon application of electricity. Ions striking the phosphor cause it to glow, emitting light. Thickness of the phosphor coating is important because it is the inner surface of the phosphor which becomes brightest. Light intensity is reduced in passing through the coating. Removing parts of the coating exposes the brilliant inner surface of the phosphor on the opposite wall. Light passes unimpeded through the window or aperture where phosphor has been removed.

Known methods of removing phosphor from one side of a tube have employed wipers which are held against one side of a tube by small leaf springs which bear against the opposite side of the tube.

The spring-pushed wiper is drawn through the tube. It is difficult to maintain alignment of the wiper with the desired aperture throughout the phosphor removing operation. However, the greatest drawback to that known method is that the spring removes a fine line of phosphor and creates a small undesired aperture directly opposite the desired aperture.

The small spring-formed aperture is responsible for a large light loss. First, the area directly opposite the clear window in an aperture tube is the area which produces the light which directly passes through the window Any loss of material or reduction in that light producing area of maximum effectiveness is immediately noticed in a reduced output of the tube. Moreover, the spring procuded aperture may provide an opening for a loss of reflected light from other areas of the tube.

It is highly desirable to construct an aperture tube without the small secondary aperture created by a spring as it supports a wiper against the opposite portion of a tubes inner wall.

SUMMARY OF THE INVENTION The present invention provides magnetic means for treating a defined area of a tube wall. The apparatus and method of the invention are particularly useful in treating a specific area on an inner surface of a tube without touching other areas of the inner wall. Treating is used with the ordinary connotation of any operation on a surface of a tube. Surface refers to a surface of a coating or a coating as well as a tube wall surface.

The method and apparatus of this invention are particularly useful in making aperture tubes by removing a phosphor coating from an area on one side of a glass tube.

The broad objects of the invention are accomplished by using a magnetic means to hold a second magnetic means against the tube wall to be acted upon. At least one of the magnetic means is a magnet; the other means may be an armature. At least one of the magnetic means, usually the armature, has a tube treating edge. Pennanent or electromagnets may be employed. The latter may be preferred so that armatures may be readily moved, aligned, joined and removed while the magnets are deenergized.

The form of magnetic means with the tube treating edge should conform to the desired surface of the tube. In most cases the tube is cylindrical. The armatures are blocks with segmental cross sections. Arcuate edges between arcuate surfaces and side faces of the blocks are square and sharp. Poles of a magnet are aligned across the tube to ensure alignment of the scraping armature within the tube. Poles are finished to a concave circular shape to fit a tube wall.

In a preferred embodiment, a plurality of magnets is assembled in a non-magnetic block. Magnets are held in spaced parallel relationship, each being aligned across a tube.

Scraping segments are assembled in spaced parallel relationship cooperatively with the magnets, with scraping edges aligned across the tubes. A resilient means, which may be multiple members or a single member, interconnects the segmental blocks. Relative movement of the blocks may occur to facilitate scraping and to match tube inconsistencies.

Arcuate surfaces of the blocks may vary from true arcs in a random or programmed manner. The variation from a true arc is preferably unique in each block. The blocks may scrape separate areas within the desired window.

One object of the invention is to operate on tubular walls, using a magnet on one wall and an armature on another wall, with one of the elements having a work- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a representation of a method of the invention in which a plurality of magnets is moved across an outer surface of a tube, drawing a plurality of armatures with scraping edges along an inner surface of the tube.

FIG. 2 is an elevational detail of magnets, scraping armatures and tube.

FIG. 3 is a sectional detail taken along line 3-3 in FIG. 2.

DETAILED DESCRIPTION OF THE DRAWING Referring to FIG. 1, a fluorescent tube is generally indicated by the numeral 1. Tube l has a glass envelope 2 and a phosphor inner coating 4. To remove the coating from a line along one side of the tube, an assembly generally indicated by the numeral 10 is used. Assembly 10 consists of a parallel array 12 of magnets 14 encased in an epoxy binder 16. The magnet array 12 is held on the outside of tube 1, while a similar array 18 of armatures 20 is positioned within the tube. Armatures 20 are held in parallel position by a flexible steel strap 22 which is bonded or welded to the backs of the armatures.

Caps 24 and 26 have nipples which receive water tubes. Water is passed through the tubes either toward the elevated end or toward the lower end or back and forth slowly while the magnetic assembly is moved back and forth along the tube 1 in the direction of arrow 28.

FIGS. 2 and 3 show a preferred embodiment of the invention in which electromagnets are employed. As shown in FIG. 2, each magnet consists of a horseshoeshaped core 14, having poles aligned across the tube 1. The poles may have concave surfaces to fit the curve of the tube. A conductor 30 has turns 32 around each core. As shown schematically in FIG. 3, terminals 34 and 36 of wire 30 are connected to a switch 38 and to power source 40.

In a preferred operation, the armature array 18 is inserted in tube 1 on the area of coating 4 to be scraped from the tube. The magnet array 12 is positioned over the armature array, and switch 38 is closed. When permanent magnets are used, the magnet array should be moved radially toward the tube in the direction of the properly placed armature array to avoid shifting of the armatures during the positioning step. The magnets, cores, windings, power supply and armatures are selected according to the desired amount of pressure normal to the tube wall that is desired. Usually a strength which is sufficient to hold the assembly with fixed relative position of the arrays is desirable. Further magnetic strength is unnecessary. In the case of electromagnets, strength of magnetic field may be precisely controlled by employing a potentiometer in the circuit.

As shown in FIG. 4, side faces 40 of scraping armatures 40 form right angles with the curved surfaces which bear against the inner wall of the tube. Scraping is accomplished at the right angle edges, and scraped debris falls into the fluid stream within the tube for removal.

The curves of the scraping armatures approximate the curve of the inner wall of the tube. Portions of the tube-abutting faces may be removed as indicated at 42, so that a different scraping arc armature is presented to the tube by successive armatures. Such a configuration has proved effective in quickly removing phosphor from a fluorescent tube. Alternately, the curves of the armatures may uniquely vary slightly from true arcs, causing the same result of individual scrapers bearing against distinct adjacent areas on the tube wall, and promoting rapid and uniform coating removal.

The varying of the surfaces from armature to armature has the additional effect of causing vibrational twisting of the resilient strap 22 as the armatures are dragged along the tube. That twisting further promotes the scraping action.

While the invention has been described with reference to one specific embodiment, it will be obvious to one skilled in the art that several modifications of the embodiment may be made without departing from the present invention. Precise limits of the invention are found only in the following claims.

We claim:

1. Apparatus for treating a surface of a tube comprising first curved magnetic means mounted within a tube for contacting a segmental part of an interior surface of the tube and for moving along an interior surface of the tube,

second magnetic means mounted on an exterior of the tube for moving along an exterior surface of the tube,

magnet means associated with one of the first and second means for drawing the magnetic means toward each other against interposed tube surfaces,

curved segmental surface treating means on one of the first and second means adjacent a portion of the tube surface and being configured cooperatively with a surface of the tube for treating the surface, 7 I

and means for moving the first and second means along the tube, whereby a surface of the tube is treated. 2. The apparatus of claim 1 wherein the surface treating means comprises a plurality of spaced multiple parallel scraping edges.

3. The apparatus of claim 1 wherein the tube is cylindrical, the second magnetic means comprises a magnet, and the first magnetic means comprises an armature having a segmental cross section, and wherein the surface treating means comprises an arcuate treating surface on the armature.

4. The apparatus of claim 1 wherein the second magnetic means comprises a plurality of aligned magnets and means to hold the magnets in spaced relationship to each other, and wherein the first magnetic means comprises a plurality of aligned segmental armatures having spaced parallel treating surfaces for engaging an interior surface of the tube, and means for holding the armatures in parallel relationship.

5. The apparatus of claim 4 wherein the magnets each have adjacent poles aligned transverse to an elongated axis of the tube.

6. Apparatus for treating a surface of a tube comprismg:

first magnetic means mounted within a tube for contacting a part of an interior surface of the tube and for moving along an interior surface of the tube,

second magnetic means mounted on an exterior of the tube for moving along an exterior surface of the tube,

magnet means associated with one of the first and second means for drawing the magnetic means toward each other against interposed tube surfaces,

wherein one of the magnetic means comprises a plurality of spaced parallel scrapers with surface treating means in the form of scraping edges being configured cooperatively with a surface of the tube for treating the surface, and a resilient means fastened to the scrapers and holding the scrapers in spaced parallel relationship, and means for moving the first and second means along the tube, whereby a surface of the tube is treated. 7. The apparatus of claim 6 wherein edges are uniquely oriented in varied segments.

8. The apparatus of claim 6 wherein the edges are substantially arcuate.

9. The apparatus of claim 6 wherein the scrapers have backs opposite the scraping edges and wherein the resilient means comprises a torsionally resilient metal strap fastened to backs of the scrapers.

10. A tube scraper comprising a plurality of segmental sections having segmentally arcuate scraping edges aligned in spaced parallel relationship, and a resilient means for holding the sections aligned and spaced.

11. The method of removing an interior coating from an axially elongated surface portion of a tube comprismg inserting a magnetic scraper having an arcuate scraping edge in the tube,

applying a magnet to an external surface of the tube near the scraping edge, thereby holding the scraping edge against an internal segmental surface of the tube, and

moving the magnet axially along the external surface of the tube, thereby drawing the magnetic scraper and the scraping edge along an internal surface of the tube and scraping a linear coating therefrom.

12. The method of claim 11 further comprising resilmoving the magnet along an external surface of the tube, thereby drawing the magnetic scraper and the scraping edge along an internal surface of the tube and scraping a coating therefrom, and

inclining the tube, plugging a lower end of the tube, and flowing water through the tube to remove scraped particles of the coating. 

1. APPARATUS FOR TREATING A SURFACE OF A TUBE COMPRISING FIRST CURVED MAGNETIC MEANS MOUNTED WITHIN A TUBE FOR CONTACTING A SEGMENTAL PART OF AN INTERIOR SURFACE OF THE TUBE AND FOR MOVING ALONG AN INTERIOR SURFACE OF THE TUBE SECOND MAGNETIC MEANS MOUNTED ON AN EXTERIOR OF THE TUBE FOR MOVING ALONG AN EXTERIOR SURFACE OF THE TUBE, MAGNET MEANS ASSOCIATED WITH ONE OF THE FIRST AND SECOND MEANS FOR DRAWING THE MAGNETIC MEANS TOWARD EACH OTHER AGAINST INTERPOSED TUBE SURFACES, CURVED SEGMENTAL SURFACE TREATING MEANS ON ONE OF THE FIRST AND SECOND MEANS ADJACENT A PORTION OF THE TUBE SURFACE AND BEING CONFIGURED COOPERATIVELY WITH A SURFACE OF THE TUBE FOR TREATING THE SURFACE, AND MEANS FOR MOVING THE FIRST AND SECOND MEANS ALONG THE TUBE, WHEREBY A SURFACE OF THE TUBE IS TREATED.
 2. The apparatus of claim 1 wherein the surface treating means comprises a plurality of spaced multiple parallel scraping edges.
 3. The apparatus of claim 1 wherein the tube is cylindrical, the second magnetic means comprises a magnet, and the first magnetic means comprises an armature having a segmental cross section, and wherein the surface treating means comprises an arcuate treating surface on the armature.
 4. The apparatus of claim 1 wherein the second magnetic means comprises a plurality of aligned magnets and means to hold the magnets In spaced relationship to each other, and wherein the first magnetic means comprises a plurality of aligned segmental armatures having spaced parallel treating surfaces for engaging an interior surface of the tube, and means for holding the armatures in parallel relationship.
 5. The apparatus of claim 4 wherein the magnets each have adjacent poles aligned transverse to an elongated axis of the tube.
 6. Apparatus for treating a surface of a tube comprising: first magnetic means mounted within a tube for contacting a part of an interior surface of the tube and for moving along an interior surface of the tube, second magnetic means mounted on an exterior of the tube for moving along an exterior surface of the tube, magnet means associated with one of the first and second means for drawing the magnetic means toward each other against interposed tube surfaces, wherein one of the magnetic means comprises a plurality of spaced parallel scrapers with surface treating means in the form of scraping edges being configured cooperatively with a surface of the tube for treating the surface, and a resilient means fastened to the scrapers and holding the scrapers in spaced parallel relationship, and means for moving the first and second means along the tube, whereby a surface of the tube is treated.
 7. The apparatus of claim 6 wherein edges are uniquely oriented in varied segments.
 8. The apparatus of claim 6 wherein the edges are substantially arcuate.
 9. The apparatus of claim 6 wherein the scrapers have backs opposite the scraping edges and wherein the resilient means comprises a torsionally resilient metal strap fastened to backs of the scrapers.
 10. A tube scraper comprising a plurality of segmental sections having segmentally arcuate scraping edges aligned in spaced parallel relationship, and a resilient means for holding the sections aligned and spaced.
 11. The method of removing an interior coating from an axially elongated surface portion of a tube comprising inserting a magnetic scraper having an arcuate scraping edge in the tube, applying a magnet to an external surface of the tube near the scraping edge, thereby holding the scraping edge against an internal segmental surface of the tube, and moving the magnet axially along the external surface of the tube, thereby drawing the magnetic scraper and the scraping edge along an internal surface of the tube and scraping a linear coating therefrom.
 12. The method of claim 11 further comprising resiliently interconnecting a plurality of scrapers having offset scraping edges, and interconnecting a plurality of parallel magnets, each having adjacent poles aligned transverse to a longitudinal direction of the tube before the inserting, applying and moving steps.
 13. The method of removing an interior coating from an axially elongated surface portion of a tube comprising: inserting a magnetic scraper having an arcuate scraping edge in the tube, applying a magnet to an external surface of the tube near the scraping edge, thereby holding the scraping edge against an internal surface of the tube, and moving the magnet along an external surface of the tube, thereby drawing the magnetic scraper and the scraping edge along an internal surface of the tube and scraping a coating therefrom, and inclining the tube, plugging a lower end of the tube, and flowing water through the tube to remove scraped particles of the coating. 